In a large saucepan over low heat, warm 1/2 cup of the tangerine juice with the sugar, stirring until the sugar is dissolved. Remove from the heat and stir in the remaining 2 1/2 cups of tangerine juice. Add the Champagne or sparkling wine. Transfer to another container and chill thoroughly.

Freeze in your ice cream maker according to the manufacturer’s instructions. Note that this will not freeze as hard as other sorbets because of the alcohol in the Champagne. However, it will make it more scoopable once fully frozen.